[hemstudent123]

Suppose that you discovered some material from another universe that obeyed the following
restrictions on quantum numbers:
n = positive integers starting from 3
0 <= l <= (n – 1)
ml = +l or –l
ms = +½, 0, or –½
Assume that the energy of the orbitals increases with n and then l, and the general concept of
Hund’s rule applies. Explain:
a) What would be the atomic numbers of the first three noble gases in that universe and
why?
b) What would be the atomic numbers of the first three halogens and why?
c) Sketch the trend of the first ionization energies of the first 9 elements.






My working:

since we are starting with n=3 and we have three spin quantum numbers, we can have three electrons in an orbital.

First Noble Gas (Atomic Number 27):
The electron configuration would be 1s³2s³2p⁹3s³3p⁹, which totals to 27 electrons.
Second Noble Gas (Atomic Number 54):
The electron configuration would be 1s³2s³2p⁹3s³3p⁹4s³3d¹⁵4p⁹
Third Noble Gas (Atomic Number 102):
The electron configuration would be 1s³2s³2p⁹3s³3p⁹4s³3d¹⁵4p⁹4d¹⁵5s³4f215p⁹.

Similarly, Halogens have one less electrons than Noble gases so our possible answers are
1) 26
2) 53
3) 101

[mjc123]

What's with the 1s³... etc. when it says n begins at 3?